Same mount (CEM40), two different OTA's:
1) C11 with OAG, coming in about 35# with the focal reducer
2) 400mm camera lens with 240mm guide scope (60mm aperture), probably 15# +/-.
While I am struggling a bit to fine tune, and I have issues occasionally, I am getting fair results with both. But one aspect is not what I expected.
In the last two sessions, when things settled down:
1) With the C11, operating at 2000mm, the total error was 0.51" (0.40 RA and 0.31" DEC) and peak errors of -2.12" RA and 1.11" DEC)
2) With the short lens and 240mm guide scope, the guiding had 1.20" total error (0.84" RA and 0.85" Dec), but quite large peak errors (3.99" RA and 2.91 DEC).
In other words, when I loaded the mount with a reasonable load, my guiding looks about half as good. Of course, my guiding focal length also dropped by a factor of 8 or so.
Neither of these are great, but the former is better than the seeing, and the latter is within one pixel on the imaging camera scale at 400mm. So ... I think acceptable.
But... does this kind of guiding error change based on focal length of the guide scope pass the sniff test? Or do I need to work harder on the light load, shorter guide length?
The guide camera in both cases is a ASI174MM-MINI by the way.